Schmidt-hammer exposure-age dating of seven paraglacial rock-slope failures in the Bolungarvík-Suðureyri area (Westfjords, Iceland)

• Published in: Geomorphology
• Main Authors: Portier, Emilie, Mercier, Denis, Decaulne, Armelle, Cossart, Etienne
• Other Authors: Laboratoire de géographie physique : Environnements Quaternaires et Actuels (LGP), Université Paris 1 Panthéon-Sorbonne (UP1)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (Nantes Univ - IGARUN), Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Humanités, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Environnement, Ville, Société (EVS), École normale supérieure de Lyon (ENS de Lyon), Université de Lyon-Université de Lyon-École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT)-Université Lumière - Lyon 2 (UL2)-Université Jean Moulin - Lyon 3 (UJML), Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet - Saint-Étienne (UJM)-École Nationale des Travaux Publics de l'État (ENTPE)-École nationale supérieure d'architecture de Lyon (ENSAL)-Centre National de la Recherche Scientifique (CNRS)-Approches Littéraires, Linguistiques et Historiques des Sources (ALLHiS), Université Jean Monnet - Saint-Étienne (UJM)-Université Jean Monnet - Saint-Étienne (UJM), Institut Polaire Français Paul-Emile Victor (PR 1266 PARI), FORESEE-SHS
• Format: Article in Journal/Newspaper
• Language: English
• Published: CCSD 2024
• Subjects: Rock-slope failures; Schmidt-hammer exposure-age dating; Landslide; Holocene; Deglaciation; [SHS.GEO]Humanities and Social Sciences/Geography; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Hraun; Bolungarvík; Suðureyri; Óshólar; Sunddalur; Iceland
• Online Access: https://hal.science/hal-04563727; https://doi.org/10.1016/j.geomorph.2024.109230

International audience Many rock-slope failures (RSF) impact Iceland's Westfjords morphology. Five RSF areas, totalling seven RSFs, were studied in the western fjords around Bolungarvík-Suðureyri: Óshólar, Minni-Hlið, Meira-Hraun, the Vatnadalur valley and part of the Sunddalur valley.The aim of this article is to provide chronological data of the RSFs and to subsequently obtain a better chronosequence of post-glacial events, none of which have yet been dated in the Westfjords. More particularly, we discuss a paraglacial hypothesis of their occurrence.For this purpose, the Schmidt-hammer exposure-age dating (SHD) method is used on the RSF deposits, and the rebound values obtained from the impacted blocks are converted to age estimates using radiocarbon ages obtained from the different sites in order to calculate a SHD age calibration. Then, we establish a chronology of the setting up of the events. In this way, seven RSFs have been dated and different chronological generations of deposit emplacement have been exhibited for some of them. Thus, various periods of instability affected mountain slopes. The Óshólar RSF is thought to have been deposited firstly at around 12,500 cal BP, the Minni-Hlið RSF at ~9800 cal BP, the Meira-Hraun RSF at ~8700 cal BP, the Vatnadalur RSFs at ~9000 cal BP, ~ 6900 cal BP, and ~ 4300 cal BP, and the Sunddalur RSF at ~9600 cal BP. These RSFs therefore correspond to so-called paraglacial events, which took place at the beginning of deglaciation of the area during the first half of the Holocene.